is a mountain situated to the south of the village of

Rhigos Rhigos () is a village and community in Rhondda Cynon Taf, Wales. The village is located on the saddle of higher ground between the Vale of Neath and the Cynon Valley. It was part of Neath Rural District, in the county of Glamorgan, until 1974. ...

in the

Cynon Valley Cynon Valley () is a former coal mining valley in Wales. It lies between Rhondda and the Merthyr Valley and takes its name from the River Cynon. Aberdare is located in the north of the valley and Mountain Ash in the south. From 1974 to 19 ...

on the south side of the upper

Vale of Neath The Vale of Neath (or Neath Valley, Welsh: ''Cwm Nedd''), one of the South Wales Valleys, encompasses the upper reaches of the River Neath in southwest Wales. In addition to the River Neath, it is traversed by the Neath Canal and the A465 du ...

and north of the

Rhondda Valleys Rhondda , or the Rhondda Valley ( ), is a former coalmining area in South Wales, historically in the county of Glamorgan. It takes its name from the River Rhondda, and embraces two valleys – the larger Rhondda Fawr valley (, 'large') and the ...

South Wales South Wales ( ) is a Regions of Wales, loosely defined region of Wales bordered by England to the east and mid Wales to the north. Generally considered to include the Historic counties of Wales, historic counties of Glamorgan and Monmouthshire ( ...

; it is the highest point in the ancient kingdom and, later, county of

Glamorgan Glamorgan (), or sometimes Glamorganshire ( or ), was Historic counties of Wales, one of the thirteen counties of Wales that existed from 1536 until their abolishment in 1974. It is located in the South Wales, south of Wales. Originally an ea ...

(Morgannwg), and the southern Welsh coalfield plateau.

Description

The summit of Craig y Llyn lies within the borough of

Neath Port Talbot Neath Port Talbot () is a Principal areas of Wales, county borough in the South West Wales, south-west of Wales. Its principal towns are Neath, Port Talbot, Briton Ferry and Pontardawe. The county borough borders Bridgend County Borough and Rhon ...

whilst its eastern slopes are within

Rhondda Cynon Taf Rhondda Cynon Taf (; RCT; also spelt as Rhondda Cynon Taff) is a Principal areas of Wales, county borough in the South East Wales, south-east of Wales. It consists of five valleys: the Rhondda Fawr, Rhondda Fach, Cynon, Taff () and Ely valleys, ...

, the boundary running in a north - south direction to the east of the summit. The name derives from the sandstone cliffs which drop steeply down to the lake on its northern side. The hill is covered by forestry, except for the steep north and northeast faces, and is crowned with a

trig point A triangulation station, also known as a trigonometrical point, and sometimes informally as a trig, is a fixed surveying station, used in geodetic surveying and other surveying projects in its vicinity. The station is usually set up by a map ...

. Several

footpaths A footpath (also pedestrian way, walking trail, nature trail) is a type of thoroughfare that is intended for use only by pedestrians and not other forms of traffic such as motorized vehicles, bicycles and horses. They can be found in a wide ...

cross near the summit of the hill, including the Coed Morgannwg Way. The highest point in Neath Port Talbot, Craig y Llyn, is commonly known as the Rhigos Mountain after the village of Rhigos located on the northern side of the mountain in the Cynon Valley. The northern slopes and lakes were designated as a Site of Special Interest because they support "...two special habitat features, and is also of special interest for a plant, the water lobelia. The first habitat feature is standing water, supporting aquatic plants typical of lakes with low nutrient content. Some of these plants are not known from anywhere further south in the UK. The second is dry

heath A heath () is a shrubland habitat found mainly on free-draining infertile, acidic soils and is characterised by open, low-growing woody vegetation. Moorland is generally related to high-ground heaths with—especially in Great Britain—a coole ...

, found on the slopes above the lakes." View of Rhigos and Llyn Fawr from Craig y Llyn

Geology

The hill is composed of a thick sequence of

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

s and

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...

s assigned to the South Wales Coal Measures. The summit plateau is formed from the

Pennant Sandstone The Pennant Measures is the traditional name for a sequence of sedimentary rocks of the South Wales Coalfield. They were also referred to as the Upper Coal Measures and assigned to the Westphalian 'C' and Westphalian 'D' stages of the Carbonifer ...

of the Upper Coal Measures. The two cwms on its northern flanks which shelter Llyn Fach and

Llyn Fawr Llyn Fawr (large lake in Welsh) is a reservoir that occupies one of a series glacial cirques that form the northern escarpment of the South Wales Coalfield uplands, overlooking the heads of the Vale of Neath and the Cynon Valley, South Wales ...

are of glacial origin. In fact, the two lakes are the southernmost glacial

tarns A tarn (or corrie loch) is a mountain lake, pond or pool, formed in a cirque (or "corrie") excavated by a glacier. A moraine may form a natural dam below a tarn. Etymology The word is derived from the Old Norse word ''tjörn'' ("a small mou ...

to occupy cwms in Great Britain. A landslip mass of rock lies above the western end of the latter lake.British Geological Survey 1:50,000 map sheet 231 'Merthyr Tydfil'

References

External links

www.geograph.co.uk : photos of Craig y Llyn and surrounding area
{{DEFAULTSORT:Craig y Llyn Marilyns of Wales Mountains and hills of Rhondda Cynon Taf Highest points of Welsh counties Sites of Special Scientific Interest in Rhondda Cynon Taf

Description

Geology

See also

References

External links